How to replace a 99 Suburban Heater Core

Can anyone offer guidance... after months and $$$ of replacing radiatior, intake manifold gasket, getting over black water (thinking I had a head gasket issue - but the shop said no after testing... see previous post http://www.automotiveforums.com/vbulletin/showthread.php?t=761393), as of last week, I FINALLY had a no-leak system. Now, all of a sudden, I had a vapor coming through the A/C vents. I also heard (what I preceived as anyway) a air popping noise - like pressure bubbling or bleeding off in the right front area of the dash. Upon getting home, I see a leak on the interior at the feet of the passenger, with wet carpet.

So - the questions:
1. Is this obviously a heater core replacement - or possibly plugged or a hose?
2. How difficult of a job is this - doe sthe A/C and Airbag have to be addressed?
Is that popping air sound an indicator that maybe I DO have a head gasket leak?

Thanks

Can anyone offer guidance... after months and $$$ of replacing radiatior, intake manifold gasket, getting over black water (thinking I had a head gasket issue - but the shop said no after testing... see previous post http://www.automotiveforums.com/vbulletin/showthread.php?t=761393), as of last week, I FINALLY had a no-leak system. Now, all of a sudden, I had a vapor coming through the A/C vents. I also heard (what I preceived as anyway) a air popping noise - like pressure bubbling or bleeding off in the right front area of the dash. Upon getting home, I see a leak on the interior at the feet of the passenger, with wet carpet.

So - the questions:
1. Is this obviously a heater core replacement - or possibly plugged or a hose?
2. How difficult of a job is this - doe sthe A/C and Airbag have to be addressed?
Is that popping air sound an indicator that maybe I DO have a head gasket leak?

Thanks



sorry for the bad news...this is most likely a heater core.......you will have to remove the whole dash...

this is not an easy repair as i'm sure you will find out when you are told the cost.......

I am sure it is the heater core - just not sure of whether a head gasket may be the cause ....

FYI - I temporarily bypassed the heater core with a U shaped hose (they sell in the Auto Parts) - quick easy - almost worth carying one with you in case the heater core ever goes out ;-)

Still looking for input on R/R and most importantly the possible cause!

I am sure it is the heater core - just not sure of whether a head gasket may be the cause ....

FYI - I temporarily bypassed the heater core with a U shaped hose (they sell in the Auto Parts) - quick easy - almost worth carying one with you in case the heater core ever goes out ;-)

Still looking for input on R/R and most importantly the possible cause!

when you remove heater core you will find the cause.....the head gasket won't cause this but!!!!!! because the head gasket failed i suspect that the coolant was not maintained properly, and upon removal of heater core this may be revealed.....if so your radiator will probably be next...the only other componet to cause this may be a bad coolant cap holding too much pressure in system, besides the corrosive coolant as a cause..

J-cat - thanks....

Just to clarify, I am not sure the head gasket is bad - were you suggesting it did? From your other comments I asssumed you said the head gasket would not cause the symptoms/results I have experienced. Correct? ;-)

Last night I removed the right seats and dried the carpet via a large fan. I reinstalled the carpet (without insulation adn jute for now) and seats. No smells apparent at this time. It was wet for 3 days and it has been moderate temps to cold here lately. So I hope no mildew.

BTW - I just checked for leaks - it was down about 10 oz. but could be from filling air pockets... keep your fingers crossed

Dexcool cooling systems need to be flushed regularly. GM recomends 5 years or 100,000 miles. In the real world, 3 years or 75,000 miles if you want to avoid problems. The Dexcool "wears out" and becomes corrosive. Electrolysis is another killer of cooling systems. To check for it, remove the radiator cap, idle the engine, put the positive probe of a digital volt/ohm meter in the coolant, put the negative probe to battery ground. Must be less than .03mv. If higher, check body and chassis grounds. After flush, install 50/50 Dexcool and distilled water. Do not use green ethylene glycol antifreeze in a Dexcool system. The green stuff is too abrasive and will destroy the water pump seal.
http://free-auto-repair-advice.blogspot.com/search/label/Dex-Cool

As far as the head gasket causing the heater core leak: If the head gasket leaked combustion pressure into the cooling system, the heater core and radiator can be weakened. If the head gasket leaked externally or into the oil, it's not likely it caused the problem with the core.

Thanks for the input…

So –‘possibly’ ? the heater core could have been damaged from a head gasket. Well – I have yet to identify if the head gasket is an issue. Currently, it appears there are no leaks in the cooling system since I have bypassed the bad heater core. I am going to take the car on a drive to see if the head gasket issue is a possibility. I assume that a leaky head gasket can be intermittent, so I may wait a few weeks before resuming /considering replacing the heater core. That said – can anyone input on the replacement or refer to a similar post?

J-cat - thanks....

Just to clarify, I am not sure the head gasket is bad - were you suggesting it did? From your other comments I asssumed you said the head gasket would not cause the symptoms/results I have experienced. Correct? ;-)

Last night I removed the right seats and dried the carpet via a large fan. I reinstalled the carpet (without insulation adn jute for now) and seats. No smells apparent at this time. It was wet for 3 days and it has been moderate temps to cold here lately. So I hope no mildew.

BTW - I just checked for leaks - it was down about 10 oz. but could be from filling air pockets... keep your fingers crossed

it appears that you head gasket is not bad if it were you would know on engine performance.

don't forget the coolant pressure cap if its causing higher than 15psi this can damage heater/radiator with cracks on tank...

when you cleaned carpet was there antifreze[pink color]or just water...this could simply be a plugged condesate drain...or a bad windshield replacement .........


If mildew is created spray under carpet on jute a 15% bleach water mixture and let air dry....this will kill musty odor/mold.......

Appreciate the input...

Well the engine runs pretty good - but can stumble when I step on it. (I think that might be the pump/regulstor under the intake manifold) But I was thinking the head gasket could seal itself depending on operating conditions and therefore be intermittent. Also - it could be pushing air into the coolant or sucking water into the motor/exhaust????

The leak was (don't shoot me) black water that is from past neglect. A few tidbits (please) ... in the past, the heater core (dash) gurgled; and once the heater core started leaking, you could hear like purging air while driving on freeway.

As for the water in the carpet, the jute was soaked for 3 days in very mild to cold weather. So I do not believe it mildewed. I peeled the entire right side carpet back, removed jute and xtra aluminum insulation (which seemed to keep the water away from the carpet) - then fan dried it for 8hrs+- till dry.

Appreciate the input...

Well the engine runs pretty good - but can stumble when I step on it. (I think that might be the pump/regulstor under the intake manifold) But I was thinking the head gasket could seal itself depending on operating conditions and therefore be intermittent. Also - it could be pushing air into the coolant or sucking water into the motor/exhaust????

The leak was (don't shoot me) black water that is from past neglect. A few tidbits (please) ... in the past, the heater core (dash) gurgled; and once the heater core started leaking, you could hear like purging air while driving on freeway.

As for the water in the carpet, the jute was soaked for 3 days in very mild to cold weather. So I do not believe it mildewed. I peeled the entire right side carpet back, removed jute and xtra aluminum insulation (which seemed to keep the water away from the carpet) - then fan dried it for 8hrs+- till dry.


head gaskets will not heal themselves they always get worse......

on the heater core, i would get a small air/foot/basket ball pump and fill heater core with 10psi and see if it leaks....put pump on one hose and air ballon or pressure guage on other hose to test for leaks....

I will do this - but I feel confident the heater core leaks as there was water all inside the car - once it was bypassed the issue stopped

I will do this - but I feel confident the heater core leaks as there was water all inside the car - once it was bypassed the issue stopped


first you say water inside vehicle...if you say coolant i would be thinking more of heater core leak..

second this heater core replacement will be quite a large job as the entire dash will require removal so therefore you want to be extra positive that its the core thats leaking....

OK - the coolant was diluted quite a bit after leaking a week and being refilled. The liquid in the cabin was initially coolant, but evolved to being just water that was rusty looking (from my previous neglect due to a long time intake manifold leak).

I hear what you are saying about the job being a big one and will follow your advice to verify the heater core isthe issue. Thanks.

I see your input on the dash having to be pulled - so I assume that would address my concern that the job is a major project and would not allow me to circumvent touching the airbag? thanks

I've done a few of those dash pulls to get to the front evaporator- which is in the same HVAC module as the heater core- it really isn't that bad to do- except you will need to recover the refrigerant- and unhook the a/c lines at the firewall- along with heater hoses- the air bags are no big deal- just unhook the battery a couple hours prior to working on the truck- the steering column needs to be pulled out entirely- but not as bad to do as it sounds- just unplug all connectors and remove the bolts and the steering pin at the base and it slides out- the dash needs to be unhooked at both sides and across the top- then pull the passenger side back about 18 inches to access the HVAC module- there are screws on the firewall side that need to be removed- then pull the entire HVAC box out of the truck and lay it on your garage floor- and disassemble it to the point where you can remove the heater core- be sure to not all the electric actuator plugs and harness routing so you can put them back appropriately. If you have patience and mechanically inclined- you can do it- forst one took me about 6 or 7 hrs- now it can be done in about 4hrs or so. The most important thing- is NEVER let the owner see his truck with the dash sitting on the passenger seat!!! it can be heart breaking to a truck lover!!

OK - the coolant was diluted quite a bit after leaking a week and being refilled. The liquid in the cabin was initially coolant, but evolved to being just water that was rusty looking (from my previous neglect due to a long time intake manifold leak).

I hear what you are saying about the job being a big one and will follow your advice to verify the heater core isthe issue. Thanks.

I see your input on the dash having to be pulled - so I assume that would address my concern that the job is a major project and would not allow me to circumvent touching the airbag? thanks

the air bag circuit has the ability to activate, even with power removed , so as has been suggested, allow a few hours of battery removal, to allow this to discharge...then it cannot deploy...